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We look at five states of matter on the site. Solids, liquids, gases, plasmas, and Bose-Einstein condensates (BEC) are different states that have different physical properties. Each of these states is also known as a phase. Elements and compounds can move from one phase to another when specific physical conditions change. For example, when the temperature of a system goes up, the matter in the system becomes more excited and active. If enough energy is placed in a system, a phase change may occur as the matter moves to a more active state.

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What is one physical characteristic of a solid? Solids can be hard like a rock, soft like fur, big like an asteroid, or small like grains of sand. The key is that solids hold their shape and they don't flow like a liquid. A rock will always look like a rock unless something happens to it. The same goes for a diamond. Solids can hold their shape because their molecules are tightly packed together.

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You might ask, "Is baby power a solid? It's soft and powdery." Baby power is also a solid. It's just a ground down piece of talc. Even when you grind a solid into powder, you will see tiny pieces of that solid under a microscope. Liquids will flow and fill up any shape of container. Solids like to hold their shape.

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The molecules in a solid are stuck in a specific structure or arrangement of atoms. The atoms still vibrate and the electrons fly around in their orbitals, but the entire atom will not change its position.

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LIQUIDS Liquids are found between the solid and gas states. Examples of liquids at room temperature include water (H 2 O), blood, and even honey. If you have different types of molecules dissolved in a liquid, it is called a solution. Honey is a solution of sugar, water, and other molecules.

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Liquids fill the shape of any container they are in. If you pour water in a cup, it will fill up the bottom of the cup first and then fill the rest. If you freeze that cup of water, the ice will be in the shape of the cup.

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Sometimes a liquid can be sitting in one place and its molecules will become a gas. That's the process called evaporation. It can happen when liquids are cold or when they are warm. It happens more often with warmer liquids. You probably remember that when matter has a higher temperature, the molecules have a higher energy. When the energy in specific molecules reaches a certain level, they can have a phase change. Evaporation is all about the energy in individual molecules, not about the average energy of a system. The average energy can be low and the evaporation still continues.

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Gases are everywhere. You may have heard about the atmosphere. The atmosphere is an envelope of gases that surrounds the Earth. In solids, atoms and molecules are compact and close together. Liquids have atoms that are spread out a little more. The molecules in gases are really spread out, full of energy, and constantly moving around in random ways.

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What is another physical characteristic of gases? Gases can fill a container of any size or shape. It doesn't matter how big the container is. The molecules spread out to fill the whole space equally. Think about a balloon. No matter what shape you make the balloon, it will be evenly filled with the gas molecules. Even if you make a balloon animal, the molecules are spread equally throughout the entire shape. Liquids can only fill the bottom of a container, while gases can fill it entirely. The shape of liquids is very dependent on gravity, while less dense gases are light enough to have a more freedom to move.

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Gas or Vapor? You might hear the term "vapor." Vapor and gas mean the same thing. The word vapor is used to describe gases that are usually liquids at room temperature. Good examples of these types of liquids include water (H 2 O) and mercury (Hg). They get the vapor title when they are in a gaseous phase. You will probably hear the term “water vapor” which means water in a gas state. Compounds such as carbon dioxide (CO 2 ) are usually gases at room temperature. Scientists will rarely talk about carbon dioxide vapor.

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PLASMA Plasmas are a lot like gases, but the atoms are different, because they are made up of free electrons and ions of an element such as neon (Ne). You don't find naturally occurring plasmas too often when you walk around. They aren't things that happen regularly on Earth.

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Plasma is different from a gas, because it is made up of groups of positively and negatively charged particles. In neon gas, the electrons are all bound to the nucleus. In neon plasma, the electrons are free to move around the system.

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The Bose-Einstein state of matter was the only one created while your parents were alive. In 1995, two scientists, Cornell and Weiman, finally created the condensate. When you hear the word condensate, think about condensation and the way gas molecules come together and condense and to a liquid. The molecules get denser or packed closer together. If plasmas are super hot and super excited atoms, the atoms in a Bose-Einstein condensate (BEC) are total opposites. They are super unexcited and super cold atoms.